Proteins

Question 1

What are the four main elements found in all proteins?

Answer 1

nitrogen

carbon

hydrogen

oxygen

Question 2

Some proteins are involved in gene expression and include ___ which assists in synthesizing RNA from DNA. Other proteins are considered defensive proteins and include ___which help destroy microorganisms.

Answer 2

RNA Polymerase, antibodies

Question 3

Proteins are made up of chains of ___ acids.

Answer 3

amino

Question 4

What are the three major structural components of an amino acid?

Answer 4

Side chain (R)

Carboxyl group

Amino group

Question 5

An amino acid may be described as nonpolar, polar uncharged, or polar charged based on the chemical properties of its ___ chain.

Answer 5

side (R)

Question 6

The main elements that make up proteins are carbon, hydrogen, __, and __, in addition to small amounts of other elements, like sulfur.

Answer 6

nitrogen, oxygen

Question 7

How do the amino acid side chains affect proteins?

Answer 7

Amino acid side chains play a critical role in the structure and function of a protein.

Question 8

Cell signaling protein function

Answer 8

Allows cells to communicate with each other

Question 9

Metabolic enzyme function

Answer 9

Increases the rate of a chemical reaction

Question 10

Transporter function

Answer 10

Aids in the movement of solutes across the plasma membrane

Question 11

Motor protein function

Answer 11

Initiates movement

Question 12

What are the monomers found in proteins?

Answer 12

Amino acids

Question 13

Which of the following accurately describes the chemical structure of a typical amino acid found in a protein?

• A central carbon is bound to a carbonyl group, an amino group, and two R groups.
• A central carbon atom is bound to an amino group, carboxyl group, a side chain, and a hydrogen atom.
• A central carbon is double bonded to both an amino group and a carboxyl group.

Answer 13

A central carbon atom is bound to an amino group, carboxyl group, a side chain, and a hydrogen atom.

Question 14

Amino acids are categorized based on:

Answer 14

their side chains

Question 15

How can amino acid side chains affect the structure and function of a protein?

Answer 15

Amino acid side chains play a role in protein folding.

Amino acid side chains are involved in catalysis at the active site of enzymes.

Question 16

What process is responsible for linking amino acids together to form polypeptides?

Answer 16

Dehydration reactions

Question 17

In a peptide bond, which parts of the two amino acids are joined together?

Answer 17

The amino group of one amino acid and the carboxyl group of the other

Question 18

When amino acids are linked together they form a large molecule called a(n)

Answer 18

polypeptide.

Question 19

Proteins are made by __ reactions, in which water is removed as amino acids are linked together to form polypeptides.

Answer 19

dehydration

Question 20

When a peptide bond is formed, two amino acids are linked between the __ group of one amino acid and the __ group of the other.

Answer 20

amino, carboxyl

Question 21

A type of covalent bond called a ___ bond forms between the carboxyl group of one amino acid and the amino group of another amino acid.

Answer 21

peptide

Question 22

A polypeptide is a chain of

Answer 22

amino acids

Question 23

Between what two atoms are peptide bonds located in the backbone of a polypeptide?

Answer 23

Carbon and nitrogen

Question 24

A free __ group is found at the N-terminus of a protein, and a free __ group is found at the C-terminus.

Answer 24

amino, carboxyl

Question 25

A protein whose highest level of structure is tertiary structure contains:

Answer 25

one polypeptide folded into its three-dimensional structure

Question 26

Where are the peptide bonds in a polypeptide located?

Answer 26

In the polypeptide backbone

Question 27

What functional groups are found at the N-terminus and the C-terminus of a polypeptide?

Answer 27

A carboxyl group is at the C-terminus. An amino group is at the N-terminus.

Question 28

What is the primary structure of a protein?

Answer 28

The amino acid sequence of a polypeptide

Question 29

What is the secondary structure of a protein?

Answer 29

The repeating pattern of folding between regions

Question 30

Match the level of protein organization with the proper description: primary

Answer 30

the linear sequence of amino acids

Question 31

Match the level of protein organization with the proper description: secondary

Answer 31

repetitive folding patterns such as α helix and β pleated sheet

Question 32

Match the level of protein organization with the proper description: tertiary

Answer 32

the three-dimensional structure of a polypeptide

Question 33

Match the level of protein organization with the proper description: quaternary

Answer 33

two or more interacting polypeptides

Question 34

What are the two types of secondary structure found in proteins?

Answer 34

β pleated sheet α helix

Question 35

Between what two atoms are peptide bonds located in the backbone of a polypeptide?

Answer 35

Carbon and nitrogen

Question 36

What type of bond is responsible for the formation of α helices and β pleated sheets?

Answer 36

Hydrogen bond

Question 37

The amino acid sequence of a polypeptide is called the ___ structure.

Answer 37

primary

Question 38

The ___ structure of a polypeptide is the repeating pattern of folding stabilized by hydrogen bonds.

Answer 38

secondary

Question 39

What level of protein organization refers to the three-dimensional shape of a polypeptide that includes all secondary structures and interactions between side chains?

Answer 39

Tertiary structure

Question 40

A protein whose highest level of structure is tertiary structure contains:

Answer 40

one polypeptide folded into its three-dimensional structure

Question 41

What level of protein structure is stabilized by interactions among the side chains of the polypeptide?

Answer 41

Tertiary structure

Question 42

The two basic types of secondary structure are the alpha __ and the beta-pleated __.

Answer 42

helix, sheet

Question 43

Proteins that have quaternary structure consist of at least __ polypeptide(s).

Answer 43

2

Question 44

The elements of a polypeptide's secondary structure, the α helix and β pleated sheets are stabilized by ___ bonds.

Answer 44

hydrogen

Question 45

What factors contribute to protein-protein interactions?

Answer 45

van der Waals effects hydrogen bonding hydrophobic effects ionic bonding

Question 46

Match each bond or interaction with the correct description. hydrogen bond

Answer 46

Bond between partial positive and negative charges on different amino acids

Question 47

Match each bond or interaction with the correct description. ionic bond

Answer 47

Bond between oppositely charged amino acid side chains

Question 48

Match each bond or interaction with the correct description. disulfide bond

Answer 48

Covalent bond between two cysteines

Question 49

Match each bond or interaction with the correct description. hydrophobic effect

Answer 49

Interaction between nonpolar amino acids

Question 50

Match each bond or interaction with the correct description. van der Waals force

Answer 50

Weak, temporary attraction between two atoms

Question 51

The three-dimensional shape of a polypeptide is the ___ structure.

Answer 51

tertiary

Question 52

Which levels of protein structure are stabilized by hydrogen bonds?

Answer 52

Secondary structure Quaternary structure Tertiary structure

Question 53

Interactions among the side chains of amino acids help to stabilize the ___ structure of a polypeptide.

Answer 53

teritary

Question 54

What level of protein structure occurs when two or more polypeptides interact with each other to form a functional protein?

Answer 54

Quaternary structure

Question 55

What type of bonds can form between positively and negatively charged side chains within a polypeptide?

Answer 55

Ionic bonds

Question 56

Interactions between different proteins can be stabilized by four main factors: __ bonds, ionic bonds, __ effect, and van der __ dispersion forces.

Answer 56

hydrogen, hydrophobic, waals

Question 57

Which of the following bonds and interactions contribute directly to a protein's tertiary structure? - Peptide bonds - Hydrogen bonds - Disulfide bonds - Hydrophobic effect - van der Waals forces - Glycosidic bonds - Ionic bonds

Answer 57

Hydrogen bonds Disulfide bonds Hydrophobic effect van der Waals forces Ionic bonds

Question 58

Hydrogen bonds can form:

Answer 58

within a polypeptide and between different polypeptide chains

Question 59

What level of protein structure is stabilized by interactions among the side chains of the polypeptide?

Answer 59

Tertiary structure

Question 60

__ bonds promote protein folding when they form between oppositely-charged side chains of a protein.

Answer 60

hydrogen

Question 61

Amino acid side chains that are nonpolar tend to exclude water and contribute to __ effects involved in protein folding.

Answer 61

hydrophobic

Question 62

What factors contribute to protein-protein interactions?

Answer 62

ionic bonding hydrophobic effects hydrogen bonding van der Waals effects

Question 63

What type of bond can form between the side R groups of two cysteine amino acids to stabilize protein structure?

Answer 63

Disulfide bond

Question 64

Which levels of protein structure are stabilized by hydrogen bonds?

Answer 64

Quaternary structure Tertiary structure Secondary structure

Question 65

Interactions among the side chains of amino acids help to stabilize the ___ structure of a polypeptide.

Answer 65

tertiary

Question 66

What functional group is involved in disulfide bridges?

Answer 66

Sulfhydryl

Question 67

Hydrophobic effects play a major role in what protein structures?

Answer 67

quaternary structure tertiary structure

Question 68

___ bridges can form between the side chains of two cysteine amino acids.

Answer 68

Disulfide

Question 69

A disulfide bond can form between two cysteines located:

Answer 69

within the same polypeptide chain or in different polypeptide chains

Question 70

When a protein is unfolded or ______, it is no longer functional.

Answer 70

denatured

Question 71

The tertiary structure of a polypeptide is predominantly determined by its __ structure.

Answer 71

primary

Question 72

Disulfide bridges are covalent bonds between ___ groups of cysteine side chains.

Answer 72

sulfhydryl

Question 73

Amino acid side chains that are nonpolar tend to exclude water and contribute to __ effects involved in protein folding.

Answer 73

hydrophobic

Question 74

A disulfide bond between two cysteines in the same polypeptide chain can help to stabilize the ______ structure of a protein.

Answer 74

tertiary

Question 75

What happens when a protein is denatured?

Answer 75

Its three-dimensional structure is disrupted.

Question 76

What is the main determinant of a protein's tertiary structure?

Answer 76

Its primary structure

Question 77

What functional group is involved in disulfide bridges?

Answer 77

Sulfhydryl